Drier



L. J. ROBB March 26, 1929.

DRIER 4 sheets-sheet 1 Filed July I3, 1925 NN Y L. J. ROBB March 26,1929.

DRIER Filed July 3. 1926 4 Sheets-Sheet lil' INVENTOR Lun-'vv 2M March26, 1929. 1 J., ROBB l 1,706,708

DRIER Filed July 5, 1926 4 sheets-sheet 5 INVENTOR -March 26, 1929.

L. J. ROBB DRIER Filed July 5, 1926 4 Sheets-Sheet INVENTOR e@ a@ @@1@ QPatented Mar. 26',l 1929,.`

y A1,106,108 `f UNirEafsrATl-:s PATENT orifice.

LWIS l2-ROBE, OF IPITTBBURGH, PENNSYLVANIA, ASSIGNOB, T0 HEYL &PATTERSON,

me., or rxTTsBUaen, rENNsYLvANIA, A CORPORATION or raNNsYLvmm mumAppnauon med'zuiy a, 192e. serial No. 120,300.

Inthe preparation of coal for pulverizing the desired capacity for theapparatus I it isy important that the coal be dried'evenly preferablyempoy a plurality of chutes and before 1t is supplied to the pulverizer.Vause a single take off means therefor. With rious schemes have beentried for this purthis arrangement the rate of .flow of ma.- pose, someof them* utilizing the gaseous erial through the entire apparatus may beroducts of combustion asa heating medium, regulated-by a singleadjustment. v The dryut these attempts have not been Wholly lng -mediumis preferably taken ofi' from successful. It is found in.v many casesthat the 'drier proper and passed to a separator the material to bedried ignites incertainl Where any cntrained material is taken there-'parts of the drier while in other parts .the from. 'moisture content isactually increased in'.` In the accompanying drawin s which i1- stead ofbeing diminished. Evenv Where ig' lustrate the present preferred emodiment of nition does not take place the material dismy invention:

Figure 1 is a side elevation showin a 'char ed from these driers islikely to be varinle as to dryness and may be said to drier with theseparator .for spent drying be streaked with moisture, and this ofvHuid; course gives rise to serious difficulties in the Figure 2 1s atop plan view of the appara,v pulverizing operation. tus shown in Figure1 but with the supply It has been proposed to i .use driers in binremoved;`A which the coal is moved in a vertical col- Figure 3 is an endelevation of the a umn between grids which act as ides for tus shown inFigure 1; the column of coal. In the use o these de- Figure 4 is avertical longitudinal section vices it is found that the velocit loftheto enlarged scale of a portion of the drier, drying gases has a tendencyto hol the coal and einst the sides of the vertical grids and thusFigure 5 is a Vertical section through a ve rise to non-uniformoperation. Also it -modified form of drier. A as frequently been foundthat the -trans- In the illustrated embodiment of the .infer of heatfrom the gases causes the coal to vention there is shown a drierindicated genheat rapidly on the incoming side and carry erally -by th'ereference character 2 compristhe moisture to the outgoing side, theresult ing an outer shell 3 having a plurality of being an unequaldrying of the coal and on inclined chutes 4 extending therethrough.occasion combustion thereof on the' incoming At the top of each chute 4is a regulating side. gate 5 and a discharge leg of a supply `bin Iprovide a drier comprisin an inclined 6. The coal or other materialflows from chute with take off means at t e bottom of the bin 6 throughthe gate 5 into the chute the chute for regulating the vflow* ofmaterial 4. At the bottom of each chute there is pro- With means forpassing a drying `fluid' vided a short vertically extending portionthrough the material in the chute. Prefer- 7 Whose bottom terminatesabove but is ably there is provided a chamber through spaced away from aplate 8. (See Figure which the chute extends. This chute is pro- 4.) Thedownflowing material tends to pile vided with a grid on the under sidethrough up on the plate 8, the material assuming its which the dryingmedium may pass land is natural angle of repose, until such llow isprovided with a screen on the upper side checked by the bottom edge ofthe vertii'or defining the thickness of the column of cally extendingchute portion 7. I have incoal to be dried. Preferably the chute isdicated by the letterI R on Figure 4 the ansupplied from a source ofmaterial adapted gle of repose for the material being handled tomaintain the chute substantially full at and I make the plates 8 of suchlength that all times as this results in uniform drying. they extendbeyond a line determined by the This supply means may constitute a binwith intersection of the line Rwith the plane of a regulating gate. theplates.

In order to secure regulation of the quan- Since the flow of thematerial from each tity of material being dried I referably chute ischecked by the plate 8 the material employ a control for the take omeans at piles up in the chute until it is substantially the bottom ofthe chute. In order to secure filled as shown in Figure 1.

ppara- .fluid to the material in the chute in such manner that bindingof the material is eliminated.

The top of each chute comprises a screen 11 which is effective fordefining the thickness of the column of material being dried.

The drying fluid, which may be waste gaseous products of combustion, issupplied to the apparatus through a conduit 12 having outlets 13 leadingto the drier 2. One of these outlets is provided for each chute in thedrier r2 and a division plate 14 is provided within the drier forcompletely isolating one chute and its gas supply system from the other.

The hot gases pass from the space within the drier below the bottomplate v 9 through the slots 10. The gases pass through the column ofcoal, drying the same, and then pass olf through the screen 11 to thespace 11 inthe drier above sugh screen. Outlets 15 are provided on theside. of the drier remote from the inlets 13 and these communicatethrough a manifold 16 with a conduit 17 leading to an exhauster 18. Theexhauster discharges into a conduit 19 leading to a cyclone collector20. This collector is effective 'for separating entraine/d particles ofdried material from the exhaust gases. The collected material isdischarged into a screw conveyor 21 by which it may be taken to thepulverizer or any other desired place. i

Referring now in more detail to the drier 2,v the chutes 4, as alreadypointed out, are inclined. These chutes may be made at any angle from 35to 50 from the horizontal but it is found that the nearer the angleapproaches 45 the more easily and uniformly will the coal flow throughthe apparatus.

The screens 11, while effective for defining the thickness of the columnof coal flowing through the apparatus, must of course be open enough topermit of free discharge of the drying gases and due to thisfact andalso due to the tendency of the drying gases to entrain small particlesof solid material, a certain amount of material may get into the spaceabove the screens 11 but still not be carried through the outlets 15 tothe conduit 17. I therefore provide a baille plate 22 which makes itnecessary for the gases to move downwardly and then upwardly, asindicated by arrows in Figure 4, in order to get out of the drier. Thesolid particles tendency seems due, at least in part, to the fact thatatmospheric gases are drawn upwardly through the coal lying in thedischarge legs 7. To offset 'this tendency, I prefer to employ one ormore flexible bailles 22b secured to the legs 7 as shown. These baffles,While they permit free action of the discharge mechanism, increase theresistance to the upward flow o-f atmospheric gases. They will have thiseffect even though they are held clear of the plate 8 by dried coal,

as in this case they increase the length of the gas path bysubstantially their own length.

When dealing with material of this character it is of course possiblefor such material to percolate into all parts of the apparatus. Thetendency of the material to sift through the grids 9 is minimized by theprovision ofthe horizontal slots 10, but hand holes 23 having suitablecover plates are provided forcleaning out the wind boxes below thechutes.

With the apparatus so far described there is no tendency for the columnsof coal to move through the apparatus because of the fact that the coalitself chokes off the flow. The means for controlling the flow of solidmaterial through the apparatus will now be described.

A pair of shafts 24 and 25 is provided at each end of the dischargechamber 26 in which the plates 8 are located and sprockets 27 yareplaced on each shaft. A pair of sprocket chains 28 extends around thesprockets 27, passing over the plates 8 near each side thereof. Thesprocket chains 28 are connected at intervals by cross bars 29 whichpass between the plates 8 and the bottom of the chute portions 7 asshown in Figure 4. These bars act as Scrapers or sweeps and areeffective for sliding the dried material over the plate 8 from which itfalls into a bin 30. When the material is swept out from under the chutethe material in the chute moves downwardly until its flow is againchecked as above described.

The speed of the discharge mechanism and therefore the rate at whichmaterial is dried in the apparatus is controlled entirely by the speedof the shaft 24. This shaft is connected through a sprocket chain 31 toadrive sprocket 32. The drive sprocket 32 -is connected to a drivingmotor 33 through a speed reducer 34 and a speed controller 35 isprovided for the motor 33. By' suitably regulating the speed controllertheflow of material through the apparatus may be regulated as desired.The flow of heating gases through the drier may be regulated by acontroller 18 connected to the motor 18m which drives the exhauster 1,8.

In Figu form of apparatus wherein each of the inclined coal chutes isformed from a plurality of staggered portions. This arrangement may beused to secure greater drying capacity. Inthis form of the inventionparts corresponding to similar parts in the first described embodimenthave been given the same reference character with a letter suffixed. Itwill be noted that each section of the chute has its own fluid supplymeans, and these are referably indepen ently regulable. It will also benoted that 1n the lower section the ses travel through -the coal fromleft to` right, while in the section thereabove they travel through thecoal from right to left.

I have illustrated and described a preferred embodiment of my inventionas particularly applied to the drying of coal. It will be understood,however, that the inven tion is not limited to the form shown as it maybe otherwise embodied within the scope of the following claims.

I claim:

1.. A drier, comprising a chamber having an inclined chute therein,means for supplying drying gases to the chamber below the chute, thechute having a perforate bottom plate to. permit passage of the dryingases therethrough, and a perforate top plate for the chute, the chamberbeing provided with a discharge outlet for material above the top late.

2. A rier, comprising a chamber having an inclined supporting surfacetherein for material to be dried, means spaced from the supportingsurface for determining the thickness of material thereon, means forpassing a drying Huid through the material,

and a discharge outlet for the material collecting above the -meanswhich determines the thickness of the material.

3. A drier, comprising an inclined chute,

.I take. olf means at the bottom of the chute,

means for passing a gaseous drying fluid from side to side through thematerial in the chute, and a baille for atmospheric gasesl at one end ofthe chute.

` 4. A drier, comprising an inclined chute,

vtake ofi' means at the bottom of the chute,

means for passing a gaseous drying fluid from side to side through thematerial in the chute, a plate spaced from the bottom of the chute, asweep adapted for movement between the plate and the bottom of thechute, and a yieldable baille in the path of the sweep.

re 5 I have shown a modifiedl 5. A drier, comprising a chamber having aninclined perforated supporting surface therein formaterial to be dried,perforated means spaced from the supporting surface for determining thethickness of material thereon, means for passing drying, fluid meansspaced from the supporting surface for determining the thickness ofmaterial thereon, means for passing drying fluid through the material,supporting surface and. spaced. means, means for causing the dryingfluid after passing through 'the spaced means, to move along the uppersurface thereof for removing particles of material deposited thereon anda discharge outlet for the material collected above the spaced means.

7. A drier, comprising a chamber having an inclined perforatedsupporting surface therein for material to be dried, perforated meansspaced from the supporting surface for determining the thickness ofmaterial thereon, means for assing drying fluid through the materia,supporting surface and spaced means, means for causing the dryin fluid,after passing through the space means, to move along the upper surfacethereof for removing particles of material deposited thereon and adischarge outlet for returning the material collected above the spacedmeans to the main body of the material.

8. A drier, comprising a chamber having an inclined perforatedsupporting surface therein for material to be dried, perforated meansspaced from the supporting surface' for determining the thickness ofmaterial thereon, means for passing drying fluid through' the material,supporting surface and spaced means, means for causing the dryin fluid,after passing through the space means, to move along the upper surfacethereof for removing particles of material deposited thereon and adischarge outlet for returning the material collected above the spacedmeans to the main bod of the material below the supporting sur ace.

9. In a drier, a chamber, a perforated chute disposed within thechamber, means for passing drying fluid through the chamber and materialtherein, and a baille for directing the drying fluid along the lee sideof the chute for removing particles of material adhering thereto.

10. In a drier, a chamber, a perforated chute disposed within thechamber, means for passing drying fluid through'the chamber and materialtherein, and a'baille for directing the drying fluid along the lee sideof the chute for removing particles of material adhering thereto and forim artingv a sudden change in the movement o the fiuid for dischargingthe particles of material.

11. In a drier, a chamber, a perforated chute disposed Within thechamber, means for passing drying fluid through the chamber and materialtherein, a battle for direct- In testimony whereof I have hereunto set20 my hand.

LEWIS J. ROBB.

CERTIFICATE 0F CDRRECTIN.

Patent No. 1,796, 708.

Granted March 26, 1929, to

LEWIS J. ROBB.

lt is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as toliows:

Page l, at the beginning of the specification, insert the iirstparagraph "This 'invention relates to driers and is particularly usefulfor the drying of coal or other material in granular form."; and thatthe said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 23rd day of April, A. D. 1929.

(Seal) M. J. Moore, Acting Commissioner of Patents.

CERTIFICATE 0F CGRRLCTTQN.

Patent No. 1,706,708. Granted March 26, 1929, to

LEWIS J, ROBB.

lt is hereby certified that errer appears in the nrintetl specificationof the above numbered patent requiring correction as ioiiews: Page l, atthe beginning of the specification, insert as tire first paragraph "Thisinvention relates to driers and is particularly useful for the drying oiceal or other material in granular form."; and that the said LettersPatent sirouid he read with this correction therein that tire same mayconform to the record ei tire case in the Patent Office.

Signed and sealed this 23rd day of April, A. D. 192,9.

M. l. Moore,

(Seal) Acting Commissioner of Patents.

